docs: update AGENTS.md and README.md for rules system, remove beads

- Add rules/ directory documentation to both files
- Update skill count from 25 to 15 modules
- Remove beads references (issue tracking removed)
- Update skills list with current active skills
- Document flake.nix as proper Nix flake (not flake=false)
- Add rules system integration section
- Clean up sisyphus planning artifacts
- Remove deprecated skills (memory, msteams, outlook)

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1772479524,
+        "narHash": "sha256-u7nCaNiMjqvKpE+uZz9hE7pgXXTmm5yvdtFaqzSzUQI=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "4215e62dc2cd3bc705b0a423b9719ff6be378a43",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}